98 



MAZIA: In the case of the phosphatase group of enzymes, an increase 

 in activity could very well indicate a degenerative change. When you are purify- 

 ing alkaline phosphatase from horse kidney, a standard operating procedure is 

 to permit the tissue to autolyze. Before autolysis, you find much less activity. 

 Activity increases as the tissue rots. There are some cases where phosphatase 

 activity is increased by digesting the tissue with trypsin. 



DUBOIS: This increase, which you are mentioning, concerns glycero- 

 phosphatase activity. In the case of ATP-ase, degenerating spleens which have 

 been ligated in situ or removed and kept at 380C, show no increase but rather 

 a marked decrease in activity. There are several other points that should be 

 mentioned. One is that as the dosage of X-rays is increased above 400 r, the 

 activity per mg. of tissue remains at the same level as after 400 r. 



Fractionation of the spleen done by Maxwell and Ashwell (9) indicated 

 that 50 percent of the ATP-ase activity is confined to the microsomes and the 

 rest is distributed throughout the other fractions, with the supernatant general- 

 ly having only a very small fraction of the activity. But if one does a crude frac- 

 tionation of the whole organ and separates it into pulp and connective tissue, there 

 is an increase in both of the fractions. The total increase in the organ cannot be 

 accounted for in this case by depletion of the population of any one type of cell. 

 Activity in the connective tissue fraction increases just as well as in the remaining 

 portion. The relative amount of connective tissue remaining in the framework 

 structure does not account for the rise in the total organ. 



MAZIA: My point was that this sort of result might not indicate en- 

 zyme formation at all, but liberation of activity by changes that one could con- 

 sider degenerative. 



DUBOIS: If this were enzyme synthesis, it would represent a 3-fold 

 increase. 



SPIEGELMAN: You can get much more than a 3-fold increase in en- 

 zyme synthesis. You can get a 1000-fold increase. The point is to decide 

 whether this is synthesis or if it isn't, and this can be done, perhaps by use of 

 suitable analogues. 



MAZIA: There is another way in which you can do it. Working with 

 the mammal, C.H. Li has observed that hypophysectomy will prevent the forma- 

 tion of tryptophane oxidase. One might get at the question of synthesis of new 

 enzyme protein by such a procedure. 



CARTER: Do you mean adaptive enzyme formation? 

 MAZIA: Yes. 



DUBOIS: This increase is not due to the presence of an enzyme acti- 

 vator in the spleen or at least to an excess of activator, because the activities 

 of spleen homogenates from irradiated and normal animals are completely addi- 

 tive. The possibility of increased enzyme synthesis is worthy of study but with 

 due consideration to the fact that we are dealing with mammalian tissues where 

 enzyme syntheses to the extent of 1000-fold increases are not often observed. 



CARTER: Would you consider that this might be analagous to the situa- 

 tion that Dr. Potter and others have described in the liberation of latent ATP-ase 

 from the mitochondrial system? 



